The Morphological Characteristics Of Ionospheric Disturbances During Typhoon Process And Its Possible Coupling Mechanism Considering Terrain

The ionosphere is an important part of the earth's space environment.When the ionosphere was strongly disturbed,the performance of satellite navigation and positioning system and various radio communication systems would be reduced due to the electronic density gradient and ionosphere irregularities.However,the characteristics and coupling mechanism of small-scale ionospheric disturbances caused by meteorological activities in the lower atmosphere are still unclear.Therefore,the ionospheric disturbances law,influencing factors and coupling mechanism caused by low-level atmospheric meteorological activities have become an important scientific issue.Typhoon as one of the most severe surface weather changes,it is particularly important to study the ionospheric disturbances characteristics in the process of typhoon.Based on multi-source data,this paper analyzed the morphological characteristics of ionospheric disturbances during typhoon process,and preliminarily discussed the possible coupling mechanism between typhoon and ionospheric disturbances under different terrain conditions.?1?Based on the rate of change in the ionospheric TEC?Total Electron Content?index TECU.min^-1?3.5 TECU.min^-1?2.5 TECU.min^-1,respectively.?2?The results of ionospheric disturbances during typhoon based on multi-source data approaching the coast or landing.?3?The possible coupling mechanism of ionospheric disturbances was discussed based on the combination of acoustic gravity waves and different terrain conditions.Combined with the terrain analysis of typhoon landing site,it was found that the typhoon landing in higher terrain was more likely to detect significant ionospheric disturbances.No significant ionospheric disturbances was detected during MANGKHUT landing in Guangdong coastal area.After its landing,HAIMA passed through Lianhua Mountain?Altitude:1336 m?,SARIKA passed through Wuzhi mountain?Altitude:1867.1 m?and MATMO passed through Taiwan Central Mountain?62 peaks in the central mountain range are more than 3000 meters high?.During their landing,ionospheric TEC disturbances were detected on the spatial scale,and the difference of TEC_GIM-IRIwere 0.5?1.5 TECU 0.5?3 TECU?0.5?3 TECU,respectively.This phenomenon can be explained by the influence of terrain on the acoustic gravity wave.When typhoons land in higher terrain,due to the drag effect of the high terrain,the high lapse rate in the air creates an ideal condition for the development of acoustic gravity waves.During the impact of the typhoon,the acoustic gravity wave can spread to the ionosphere height and have an impact on the ionosphere.